In the particular case of wands, the DC is 20. Your target should be +10 Use Device, so you can take 10 and succeed (I'm thinking cure wounds wands here for the most part, which will probably be used out-of-combat). You really only need higher skill for scrolls and faking race/alignment (which I rarely feel the need to do).
If you had the luck/foresight enough to have an 18 Charisma, you can have a +8 in Use Device as a level 1 rogue. That other +2 can be obtained by (1) 2 more levels of rogue - level 3 is a good breakpoint for multi-classed rogues, (2) somehow obtain a +4 Cloak of Charisma, or (3) Skill Focus. The first option's probably the best... you probably want to do something else with your feats and (2) is probably out of your price range. If you're not worried about eventually casting 9th level spells, you can even take more rogue levels to make up the difference before it hits +10.
I think something (or exactly) like this was in a Dragon magazine as a "Power Play". You really need the Charisma for it to work, though.